This application relates to shaft coupling devices and more particularly to a shaft coupling device which will allow removal of a portion of a shaft between two bearings.
There are many types of machinery used in mail handling and applicable for processing it. Examples of such equipment are illustrated in U.S. Pat. Nos. 2,325,455 entitled "Envelope Handling Machine," and 3,368,321 entitled "Inserter." Such apparatus is particularly useful when a large number of envelopes are processed for mailing, and wherein each envelope is to have one or more inserts added automatically to the envelope before it is sealed. This equipment can be relatively simple, or as the number of inserts is increased, and selection of the inserts is desired, the complexity of the machine increases. Some of these machines have progressed to complete automatic mail handling systems wherein the mail piece is read by optical character recognition equipment; the desired inserts are selected and inserted into the envelope; the envelope is sealed, weighed, and then stacked with visual indication of zip code breaks in the stacked mail. This sophisticated machinery requires numerous mechanical devices to manipulate the envelopes and inserts throughout the system.
Other related equipment is illustrated in U.S. Pat. No. 4,124,435 entitled "Label Cutting Head" wherein address labels are individually cut from a web having many labels, and then applied to the mail piece. It is imperative that the mail piece be positively and accurately moved at precise times in the machine cycle. This is made possible partially through the mechanical movement of several long shafts such as shaft 24, 36 and 38. Some of these shafts are supported by bearings or bearing blocks such as illustrated at the end of shaft 38 by bearings 40. A cuttting blade 46 is operated responsive to the rotation of shaft 38. Outward of bearing 40 is a gear 62 which is connected through a complex drive mechanism to the power input. Thus, the blade 46 is operated in response to the power input through the gear system.
A problem arises in this type of equipment which heretofore has not been solved. Particularly, when the shaft is supported by two bearings, and there is a driving or driven gear outward of the bearings, it is extremely difficult to remove the shaft and replace any worn parts without an extensive amount of disassembly being required. Normally, the complete shaft must be removed from the machine which of itself is a difficult operation unless the bearings are of the type permitting easy removal, such as split bearings. However, if roller bearings are used, this presents the additional problem of slipping the shaft out from the bearings.
A second problem, which is even more difficult to solve than the first, is that removal of the shaft causes the device which is operated off the shaft to be out of time with the rest of the machine. For example, looking at FIG. 2 of U.S. Pat. No. 4,124,435, if shaft 38 is removed from the machine, then the cutting blade 46 which is operated responsive to movement of shaft 38 will be out of time with the rest of the machine unless the machine is retimed such that the cutting blade operates at the proper time in the machine cycle. Thus, retiming is necessary each time the cutting blade 46 has to be removed from the machine due to the wearing out and replacement of bearings 42. A similar problem occurs in this patented device when the feed rollers 22 must be removed due to wear and replaced with new rollers. In fact, this problem occurs often in this type of machinery whenever there are rollers, bearings, or belts which require replacement on a shaft between two bearings supporting the shaft.
A third problem in servicing this machinery is that the components and shafts are closely mounted with little room to manipulate tools or the serviceman's hand. Thus, the more work which must be done to replace components, the more difficult it is to disassemble and re-assemble the machine. For these reasons the maintenance costs involved in this type of equipment is extremely high. A qualified, well-trained serviceman is required to remove the shaft and to retime and reset the entire machine. If the time and training of the serviceman could be reduced, maintenance costs would be proportionately reduced.
One solution to this problem is to attempt to mount high wear items, such as belts and rollers outward of the bearings. Thus, they can be mounted to the shaft and merely slid off the end of the shaft when replacement is necessary. However, this is not always possible or feasible, and the items often have to be mounted between the bearings.
Another solution has been to use split rollers in place of solid rollers when feeding paper and such a substitution is possible. However, this option is not always feasible because of the discontinuity of the roller as compared to a roller made of one piece. If the system can operate with these greater tolerances, the split roller is an alternative. When belts must be replaced, laced or releasable-type belts have been used with some success. Again, this solution is not always available because of the discontinuity of the belt or the greater possibility of tearing or breaking.
Another alternative considered is to make the shaft of several shafts using hub couplings to join the shafts. However, this approach is not practical as the shaft must be machined to receive the hub. This greatly increases the cost of this alternative. Also the hubs take up more room than the diameter of the shaft and there is not sufficient clearance for the hubs in the machinery. A hub is also difficult to reach by the serviceman as the bolts holding the hub together are difficult to get to with tools as they are in alignment with the shaft and not easily accessible. Another shortcoming of using hub couplings is that the alignment of the shafts coupled is not always within the close tolerances required by the mail processing equipment. Thus, there is a need to provide an improved alternative to service mechanical equipment having wear components located on a shaft between the bearing supports. Furthermore, there is a need to provide a less expensive solution to this problem than the previously described methods. Furthermore, it is desired to provide means to replace worn components mounted on a shaft between two bearings without causing the remainder of the machine to be retimed with respect to the components replaced.
Applicants' invention provides another alternative for solving the above-described problem. The inventive solution is to uniquely split and couple the split shaft so that a section of the shaft between the two bearings can be removed. This allows replacement of the components or replacement of the belts on the shaft portion removed. Furthermore, the shaft can be removed and reassembled easily, with accurate alignment of all coupled shafts. The strength and rigidity of the entire shaft assembly is not compromised. Furthermore, this inventive solution does not require any specialized training of the repairman, nor does the repairman have to be able to retime the entire machine. Also, the repairman has open easy access to the coupling, as he works on the coupling from a radial orientation rather than axially.
The solution which Applicants have devised is to split the main shaft into preferably three shafts. The first and second shafts are retained at all times within their respective bearings. Between these two shafts is a coupling shaft which is designed to be removed from engagement with the first and second shafts. At each end of the coupling shaft and at the ends of the first and second shafts, between the bearings, is a coupling piece integral with the shafts. The coupling pieces on the shafts are complementary with one another such that the coupling pieces on the coupling shaft engage the respective coupling pieces of the first and second shafts. A collar is placed around the coupling pieces after engagement to hold the shafts together. There are locating pins along the shafts to accurately position the collar around the coupling pieces which further aids the serviceman in the maintenance procedure. The coupling pieces can take several forms. One which proved to be very satisfactory was to form the ends of the shafts in semicylindrical portions which are complementary with one another. Thus, a collar can be slipped around the coupling pieces and the entire shaft maintains its cylindrical contour over its entire length. A pin or key centrally located with the coupling piece also aids in proper shaft alignment.